Lightning-arrester



C. T. ALLCUTT.

LIGHTNING ARBESTER.

APPLICATION HLED SEPT. 1. I917- 1,361,801 Patented Dec. 14, 1920.

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HOUSE ELECTRIC AND MANUFACTURING COMPANY, A CORPORATION OIJENNSYL- VANIA.

LIGHTNING-ARRESTEIR Specification of Letters Patent.

Patented Doc. 14, 1920.

Application flled September 1, 1917. Serial No. 189,348.

T 0 all whom it may concern:

Be it known that I, CHESTER T. ALLoU'r'r, a citizen of the United States, and a resident of Wilkinsburg in the county of Allegheny and State of Pennsylvania, have invented a new and useful Improvement in Lightnin -Arresters, of which the following is a speci cation.

My invention relates to molded articles composed partly of electrical conducting material, such as comminuted carbon in the form of graphite or some other material capable of being molded, and an electrical insulating material known as a phenolic condensation product, such as bakelite.

This invention has been developed with particular reference to articles having certain portions that are of relatively high electrical conductivity and other portions that adequately insulate these conducting portions while serving as rigid mechanical supports for them in order that the articles may be handled expeditiously without exercising undue care and be subjected to severe strains and stresses without undergoing deterioration.

In the present instance, I describe my invention as utilized in manufacturing a portion of a lightning arrester in which the electrodes thereof are separated from, and maintained electrically independent of, each other by reason of a molded article embody ing my invention.

11 excess-voltage protective devices, and more especially in protective devices for telephone or telegraph service, it is customto separate the electrodes of such de vices by means of insulatin spacers that are erforated. in any suita le manner to provide an intermediate air-gap. After an arrester of this type has been subjected to a few discharges, it is usually of no further service as a protective means until certain replacements have been made, thereby restoring it to its original condition. One defect of such an arrester is that the spacer loses its insulatingproperty. Also, nely divided particles, loosened from the electrodes by the discharge, frequently lodge in the air-gap between the electrodes, thereby grounding the associated circuit.

In an arrester comprising an article of my invention, the electrodes may be spaced from one another without employing an insulatin spacer, since the insulating portion thereo or that portion made of bakelite, serves as a means for insulating the electrodes from each other and, at the same time, as a mechanical support for the conducting p/prtion that is integrally formed therewith.

oreover, these molded articles may be readily manufactured in large quantities without performing any expensive labor on them, such as machine work, in order to insure the production of air-gaps of uniform size between the conductin portions thereof and the electrodes with WhlCh the molded articles are to be associated. These molded articles do not undergo any serious deterioration when in service, because the lines of elec' trical demarcation between the conducting and insulating portions and the integral me chanical connection are continually maintained. Furthermore, the insulating member is never subjected to the action of an electrical discharge and the deterioration resulting therefrom.

For a better understanding of the nature and scope of m invention, reference may be had to the followingdescription and the accompanying drawing, in which Figure 1 is a front view of a protective device comprising an article manufactured in accordance with my invention; Figs. 2 and 3 are views, partially in elevation and partially in section, taken along the lines IIII and IIIIII, respectively, of Fig. 1; Fig. 4 is a front view of a molded article constructed in accordance with my invention; and Figs. 5, 6, 7 and 8 are views showing successive stages in the manufacture of the article shown in Fig. 4 and are illustrative of a method of manufacturing other articles in accordance with my invention.

Referring to Fig. 1, an insulating block 1 is provided with a recess 2 in which electrodes 4 and 5 are seated. Conducting portions 6 and 7 of the electrodes 4 and 5, respectively, are engaged by spring clips 8 and 9 that are, in turn, supported from terminals 10 and 11. 'Ihe terminals 10 and 11 are adapted to be connected to conductors of the electrical circuit which it is desired to fprotact against excess voltages by means 0 he lightning arrester. Aterminal 12 connected to a-conducting plate 13, which 1s retained in the recess 2, serves to provide a ground connection for the lightning arrcster.

Referring to F i 2, it will be noted that the conducting pFate 13 is connected, by means of a clip 14, to the terminal member 12 and that an electrode 15, associated with the electrode 4 is maintained in electrical contact with the conductin plate 13 by means of the pressure exerte by the spring clip member 8. A conducting electrode, like electrode 15, cooperates with the electrode 5 and is maintained in contact with the plate 13 by the clip member 9.

In Figs. 3 and 4, the electrode 4 is shown as comprising an insulating portion 16 and a central conducting portion 17. A channel or groove 18 is formed along the line of separation between the ortions 16 and 17, the outer periphery 19 0 which is spaced a suflicient distance from the outer edge of the conducting portion 17 to preclude any electrical discharges from comin into contact with the insulating portion 0% the electrode which would, in time, decompose it and thereby destroy its insulating properties. It will be understood that the 111118! surface of the conducting portion 17 is countersunk with reference to the inner surface of the insulating portion 16., As a consequence, a gap 20 is formed between the opposing surfaces of the conducting portion 17 and the electrode 15. This gap is maintained unobstructed, since all loosened particles from the electrodes are received in the groove 18. Thus the continuous operation of the ar rester is insured.

The molded electrode 4 may be manufactured by the use of a mold 21, as shown in Fig. 5, that is provided with an opening of substantially the same size as the article to be molded. The bottom of the opening is provided with a lower surface 22 and with an upper surface 23 that is separated from the ormer by means of an upwardly-projectin lip 24. A plunger 25 having, in eneral, t e shape shown in the drawing is rst inserted into the opening in the mold. An insulating molding mixture 26, comprising bakelite suitably combined with a filler, suc

. as wood flour, is then poured into the annular opening. An annular plunger 27, embracing the plunger 25, is ressed downwardly in order to compress t e bakelitematerial 26 to such a degree as will insure maintenance of its shape after the plunger 25 is withdrawn from the mold. It is to be understood that this operation is effected while the mold is heated to such degree as to make the molding mixture 26 slightly plastic. Theplunger 25 is then withdrawn from the mold and a mixture 28 is admitted into the space formerly occupied by it, as shown in Fig. 7. The mixture 28 comprises bakelite and a comminuted conducting material which may be graphite, lampblack or any other suitable material. A plunger 29, equal in diameter to the plunger 25 and equal in length to the annular lun or 27 is then inserted, as shown in l ig. The mold is then placed in a hot press and the material is subjected to the combined action of heat and pressure, which is necessary to properly cure the phenolic condensation product or bakelite.

By reason of the bakelite in the mixtures 26 and 28, an autogenous joint is secured between the compressed conducting portion 17 and the insulating portion 16, as shown in Fig. 8. The insulating portion 16 and the conducting portion 17 are joined to one another by means of a multitude of connections that result from the simultaneous setting? of the bakelite in the two separate portions of the article. In this manner, the insulating portion 16 serves to mechanically support the conducting portion 17 while, at the same time, the two portions are maintained electrically independent of each other.

\Vhile I have shown and described a sin gle article onlyinvolving my invention and a method for manufacturing the same, it will be understood that I desire such limitations only to be imposed upon my.invention as are pointed out in the appended claims.

I claim as my invention:

1. An article of manufacture com rising an insulating portion containing a p enolic condensation product and an electrical con ducting portion molded integrally therewith and comprising a comminuted electrical conducting material.

2. An article of manufacture comprising an insulating portion containing bakelite and a conducting portion molded inte rally therewith and comprising comminute 0on ducting carbon.

3. An article of manufacture com rising an insulating portion containing a enolic condensation product and an electrical c0nducting portion molded into rally therewith and comprising comminute conducting carbon mixed with a phenolic condensation product.

4. An article of manufacture comprising an insulating portion containing bakelite and an electrical conductin portion comprising comminuted graphite mixed with bakelite.

5. An article .of manufacture comprising an insulating portion containin a phenolic condensation product and a con uctmg portion molded integrally therewith and comprising a mixture of comminuted electrical conducting material and a phenolic condensation product.

6. The method of forming a member for av lightning arrester which consists in molding an insulating support containing a phenolic condensation product and thereafter molding integrally therewith an electrical conducting portion comprising a comminuted conducting material and a binder therefor to each other.

8. The method of forming an article of manufacture which comprises the separate lacing in a mold of a mass containing akelite and thereafter a mass comprising a mixture of bakelite and graphite, the whole being subjected to heat and pressure in order to form an autogenous union between said two masses of material.

9. A protector comprisin a pair of electrodes, one of said electro es comprising a conducting member and the other comprising a non-conducting portion and a conducting portion autogenously connected thereto the surface of said conducting portion being countersunk relatively to the corresponding surface of the insulating portion and being separated therefrom by means of a groove.

10. A protector comprising a pair of electrodes, one of which comprises a conducting member and the other a non-conductin molded portion and a conducting molde portion that are autogenously joined to each arrester com rising a other, the o posin conducting surfaces of said electro es, w on placed in op osition to each other, being in relatively ifl'erent planes and a groove being formed along the line of separation between the conducting and non-conducting portions of said second electrode in order to preclude electrical discharges from coming into contact withthe non-conducting portion of said second electrode. A

11. A discharge electrode for a lightning arrester comprising a lurality of refractory conducting partic es held in a binder of phenolic condensation product.

12. A discharge electrode for a lightning lurality of carbon particles hel in a bin er of phenolic condensation product.

13. In a protective device, a discharge gap comprising two opposing and relatively spaced members, each of which comprises a plurality of refraptory conducting particles held in a binder of phenolic condensation product.

-14E. In a protective device, a discharge gap comprising two opposing and relatively spaced members, each of which comprises a plurality of carbon particles held in a binder of phenolic condensation product.

In testimony whereof I have hereunto subscribed my name this 21st day of August, 1917.

CHESTER T. ALLCUTT. 

